You can see the boot that covers the terminal nut if you remove the right side fairing panel. You may be able to pull the boot off the nut with some long needle nose pliers but you will risk damaging the boot. If you try this then make sure you disconnect the ground from the battery. If you touch that nut or wire and the chassis, you will get a light show.
Only take about 5 minutes to remove the tank. I have done it even with a full tank. It is heavy, but it can be done. That is the best approach.
Also, be careful with that conductive grease especially with this connection. It is warm under there and if that grease runs it will hit ground somewhere. Keep in mind the entire alternator housing is ground. You are better off with di-electric grease or good old vaseline if you want to prevent moisture on the terminal.
I still don't believe corrosion is the issue here. It is more related to a loose connection either at the terminal nut or a bad crimp on the terminal itself leading to increased resistance, voltage drop and heat. My 2012 showed no signs of corrosion but the nut itself was somewhat loose. I only lost about 0.2 or 0.3volts at idle so the heat from the added resistance was still manageable by the wires.